Piston-actuated endoscopic tool

ABSTRACT

Endoscopic apparatus is provided, having a distal end ( 102 ) for insertion into a body of a patient and a proximal end that is held outside the body of the patient. The apparatus includes a proximal cylinder ( 404 ), disposed in a vicinity of the proximal end of the endoscopic apparatus. A proximal piston ( 406 ) is slidably contained within the proximal cylinder. A distal cylinder ( 328 ) is disposed in a vicinity of the distal end of the endoscopic apparatus, and a distal piston ( 310 ) is slidably contained within the distal cylinder. A tube ( 402 ) for containing a liquid is coupled between the proximal and distal cylinders. A tool (e.g., biopsy tool  115 ) is coupled to be actuated by displacement of the distal piston, so as to perform a mechanical action on tissue of the body or contents of the body, responsive to displacement of the distal piston.

FIELD OF INVENTION

The present invention relates generally to actuation of tools forflexible medical devices, and specifically to methods and devices foractuating endoscopic tools during medical procedures.

BACKGROUND OF INVENTION

The use of an endoscope for examining a body cavity is well known in theart. The diagnostic and therapeutic advantages conferred by directexamination of the gastrointestinal tract with a flexible endoscope havemade this method a standard procedure of modem medicine. One of the mostcommon endoscopic procedures is colonoscopy, which is performed for awide variety of purposes, including diagnosis of cancer, determinationof the source of gastrointestinal bleeding, viewing a site affected byinflammatory bowel disease, removing polyps, and reducing volvulus andintussusception.

Flexible endoscopes typically include working channels, which run thelength of the endoscope. One of the uses of these channels is to passtools through the endoscope for performing diagnostic and therapeuticprocedures within the body. Such tools include, for example, miniaturebiopsy forceps, which are passed through the channel and extend outthrough the distal end of the endoscope to take biopsy samples from thearea under examination. Such tools are commonly controlled by means ofcables or wires passing through a sheath, behind the tool itself, to thedistal end of the endoscope. Tension is applied by a physician at theproximal end to the cables or wires, in order to induce a desired actionof the tool at the distal end.

The extent to which the tool can be actuated by this technique islimited by friction between each wire and a sheath surrounding the wire.In particular, if a physician needs to overcome only a single turn inthe gastrointestinal tract, then the force F1 that must be applied atthe proxin al end in order to generate a force F2 at the distal end canbe approximated as F1=F2*_(e)μα, where μ is the coefficient of frictionbetween the wire and the sheath, and a is the effective angle defmed bythe turn in the gastrointestinal tract. If, as is conunon, the endoscopetravels through a number i of turns α_(i) i in the gastrointestinaltract, then the total force can increase significantly (and oftenprohibitively) to F1=F2*_(e) ^(μΣ|α) _(i) ^(|.)

To overcome the effects of friction incurred using wire-in-sheath basedsystems, attempts have been made to introduce hydraulics to endoscopes,but none of these have been commercially viable. All such hydraulicsystems known to the inventor are complicated, expensive, bulky and/orrequire external power or pressure sources, as well as the equipment tomanage these sources. Because of these drawbacks, only wire-basedtechniques are currently used for endoscopic steering and tool-controlapplications.

U.S. Pat. No. 5,569,299 to Dill et al., which is incorporated herein byreference, describes an endoscopic urological biopsy forceps with onestationary jaw and one moveable jaw, wherein the moveable jaw isactuated by a wire that runs internal to a hollow tube supporting thetwo jaws. The forceps is operated via actuation of the wire at theproximal end by a healthcare professional.

U.S. Pat. No. 5,431,645 to Smith et al., which is incorporated herein byreference, describes techniques for remote activation of endoscopictools by various types of power sources including electric, mechanical,hydraulic and pneumatic sources located near the proximal end of theendoscope.

U.S. Pat. No. 5,779,646 to Koblish et al., which is incorporated hereinby reference, describes a deflectable biopsy catheter wherein controlwires running from the proximal to the distal end of the catheter areused to deflect the distal tip and/or activate the biopsy jaws. Thecontrol wires are attached to a piston, which is seated in a cylindercontained in a handle at the proximal end of the catheter, such thatmovement of the piston allows the operator to control the deflection ofthe distal tip and/or to activate the biopsy jaws.

U.S. Pat. No. 5,674,205 to Pasricha et al., which is incorporated hereinby reference, describes a device for delivering a drug to a site withina lumen oof the body. The device resembles an elongated syringe with adistal piston/needle device containing a dose of drug, wherein aphysician-operated end of the syringe is used to actuate the distaldevice via a fluid-filled tube connecting the distal and proximal ends.

U.S. Pat. No. 6,059,719 to Yamamoto et al., which is incorporated hereinby reference, describes an endoscope system which contains a pluralityof endoscope modules having different treatment instruments mountedtherein, wherein the various treatment modules are freely exchangeable.In some embodiments, requisite forces to actuate the treatment modulesare supplied via a transmission wire that traverses the length of theendoscope. Other embodiments, contain a liquid filled channel connectinga distal piston/cylinder arrangement to a proximal means of deliveringfluid pressure, so as to move the distal piston. A transmission wireconnects the distal piston to a treatment module such that movement ofthe distal piston actuates the treatment module.

A paper by Peirs et al., entitled, “A Micro Robotic Arm For A SelfPropelling Colonoscope,” published in Proc. Actuator 98, 6th Int. Conf.on New Actuators, pp. 576-579, June 1998, which is incorporated hereinby reference, describes a self-propelling endoscopic system forcolonoscopy that comprises a flexible arm, which is controlled by shapememory alloy materials, to which are attached endoscopic tools. Theendoscopic tools are controlled by either heating/cooling of shapememory alloy mechanisms, or by hydraulic means via a distalpiston/cylinder apparatus. A simple piston/cylinder apparatus is usedwith a single pressure port on the cylinder, such that both positive andnegative pressures must be used to operate an attached tool.

SUMMARY OF THE INVETION

It is an object of some aspects of the present invention to provide animproved system and method for actuating a tool within a lumen.

It is a further object of some aspects of the present invention toprovide an improved mechanism for actuating a tool within a body cavityof a patient for purposes of examination, diagnosis, or treatment.

It is still a further object of some aspects of the present invention toprovide an improved mechanism for actuating a tool within a body cavityof a patient for purposes of obtaining a tissue biopsy or performinganother procedure.

In preferred embodiments of the present invention, an endoscopic toolfor performing a mechanical action on tissue or contents of thegastrointestinal tract of a patient or within another body cavity, isadvanced through a channel in a flexible endoscope placed in the cavity.The endoscopic tool is brought into proximity with a target (e.g.,tissue, an intestinal calculus, or a stone), and is actuated with theaid of an actuation mechanism. coupled to the tool, near the distal endof the channel, to perform a mechanical action on the target. Theactuation mechanism comprises one or more cylinders, each containing apiston, whereby movement of the pistons actuates a linkage, coupled tothe tool, causing the tool to function. Movement of the pistons isachieved by introducing liquid into or removing liquid from thecorresponding cylinders. The liquid is delivered from the proximal endof the endoscope to the cylinders of the actuation mechanism near thedistal end of the endoscope via a closed system of one or more flexibletubes, passing through the working channel. These embodiments of thepresent invention obviate the need for tool-actuating wires running thelength of the endoscope, thus minimizing difficulties, such as friction,which are commonly associated with wire-based actuation.

Preferably, the tool is actuated by pressurizing the pistons in theactuation mechanism, by driving fluid under pressure into the pistons,rather than by withdrawing fluid from the pistons as inhydraulically-actuated tools known in the art. In the context of thepresent patent application and in the claims, “actuating” the toolrefers to perfomiring an operation requiring force to be exerted by thetool, such as closing a biopsy forceps. In actuation mechanisms based onwithdrawing fluid from a hydraulic mechanism, only one atmosphere ofnegative pressure can be applied, so that forces applied by the tool arelimited. When liquid is driven into the pistons under positive pressure,much greater forces can be applied.

Means for providing liquid to the cylinders in the actuation mechanismvia the flexible tubes are preferably located near the proximal end ofthe endoscope, external to the patient. In a preferred embodiment of thepresent invention, a drive-piston/cylinder system is used to providepressure to the liquid in the flexible tubes, so as to drive theactuation mechanism. Preferably, the operator uses hand and/or footmovements to displace one or more drive pistons in their respectivecylinders, resulting in movement of liquid into or out of the actuationmechanism cylinders, and thus movement of the corresponding pistons andthe desired actuation of the tool near the distal end of the endoscope.Thus, physical forces applied by the operator are directly orproportionately applied to actuate the endoscopic tool, providing theoperator with a sense of feedback. After a relatively short training andpractice period, the operator typically learns the amount of forcenecessary to apply to a mechanical user-interface device such as ajoystick, in order to operate the tool during a particular procedure.Leveraging, or other aspects of the mechanical and/or hydraulic designof the actuation mechanism, control the physical force required toactuate the tool.

In a preferred embodiment of the present invention, each actuationmechanism cylinder comprises one port for introduction or withdrawal ofliquid so as to move the corresponding piston. The pistons divide eachactuation mechanism cylinder into two regions: (a) a liquid-transferregion, comprising a port through which liquid is actively added orwithdrawn, and (b) a passive region, which may be open at one end, orwhich may comprise a spring or a fixed amount of a compressible fluidsuch as air. Preferably, the actuation mechanism cylinder is alignedwith the longitudinal axis of the endoscope, and the liquid-transferregion is closer than the passive region to the distal end of theendoscope. This arrangement is preferred for some applications, becausewhen liquid is added to the distal end of one of the actuation mechanismcylinders, a tensile force develops in members of the actuationmechanism that connect the piston to the tool, reducing the possibilityof buckling of the thin members due to compressive loads. Mechanicallinkages between two or more of the actuation mechanism cylinders arepreferably designed so as to maintain tensile loads in these actuationmechanism members when liquid is added to the liquid-transfer regions ofone or more of the cylinders. Alternatively or additionally, one or moresuitably-configured rods are coupled to the actuation mechanismcylinders so as to be placed in compression during application orremoval of liquid in the liquid-transfer region of the cylinder(s), andto thereby facilitate actuation of the tool.

For applications in which the passive region of each actuation mechanismcylinder contains a compressible fluid (e.g., air), the fluid typicallyfunctions essentially as a spring, and acts to return the piston to itsequilibrium position. Alternatively or additionally, this regioncomprises a solid spring to assist in returning the piston to itsequilibrium position once no external pressure is applied to tlecylinder.

In another preferred embodiment of the present invention, each actuationmechanism cylinder comprises two ports, one on each side of the piston,which are coupled respectively to two liquid-transfer regions of thecylinder, into or out of which liquid is actively added or removed.Flexible tubes convey hydraulic pressure from the proximal end of theendoscope to each port Movement of a given piston in the actuationmechanism is initiated responsive to the difference in the pressure onopposing sides of the piston. By regulating the pressure on each side ofthe piston, accurate control of the force delivered by the piston to theactuation mechanism linkage is achieved. Preferably, the pressure ispositive on both sides of the piston, during respective periods ofactuation of the tool.

There is therefore provided, in accordance with an embodiment of thepresent invention, endoscopic apparatus having a distal end forinsertion into a body of a patient and a proximal end that is heldoutside the body of the patient, the apparatus including:

a proximal cylinder, disposed in a vicinity of the proximal end of theendoscopic appa-atus;

a proximal piston, slidably contained within the proximal cylinder;

a distal cylinder, disposed in a vicinity of the distal end of theendoscopic apparatus;

a distal piston, slidably contained within the distal cylinder;

a tube for containing a liquid, coupled between the proximal and distalcylinders; and

a tool coupled to be actuated by displacement of the distal piston, soas to perform a mechanical action on tissue of the body or contents ofthe body, responsive to displacement of the distal pistonl

In an embodiment, the tool, the distal cylinder, the distal piston andthe tube are adapted to be passed through a working channel of anendoscope so as to access a region within the body using the endoscope.

In an embodiment the tool is adapted to access a portion of agastrointestinal tract of the patient.

For some applications, the tool includes a biopsy tool. Alternatively oradditionally, the tool includes a therapeutic tool.

In an embodiment:

(a) the distal cylinder has two regions, on respective sides of thedistal cylinder,

(b) the tube is adapted to be in communication with a first one of theregions,

(c) a second one of the regions is configured such that motion of thedistal piston in a first direction changes a fluid pressure in thesecond region, and

(d) the distal piston is coupled to the distal cylinder so as toexperience a force in a second direction, opposite to the firstdirection, responsive to the change in fluid pressure.

For some applications, the proximal piston is adapted to be handoperated. In an embodiment, the apparatus includes a linkage, coupled tothe proximal piston, which is adapted to facilitate hand operation ofthe proximal piston.

For some applications, the tool is coupled to the distal piston so as tobe actuated by pressurization of the tube by the liquid due to operationof the proximal piston. For example, the tool may include a forcers,anld actt]ating the tool by pressurization of the tube causes theforceps to close. Alternatively, the tool includes a snare, andactuating the tool by pressurization of the tube causes the snare toclose.

There is further provided, in accordance with an embodiment of thepresent invention, endoscopic apparatus having a distal end forinsertion into a body of a patient and a proximal end that is heldoutside the body of the patient, the apparatus including:

a distal piston;

a distal cylinder within which the distal piston is slidably contained,and which is in a vicinity of the distal end of the endoscopicapparatus, the distal cylinder having a first distal port proximal tothe distal piston and a second distal port distal to the distal piston;

a tool coupled to be actuated by displacement of the distal piston;

a proximal piston;

a proximal cylinder within which the proximal piston is slidablycontained, and which is in a vicinity of the proximal end of theendoscopic apparatus, the proximal cylinder having a first proximal portproximal to the proximal piston and a second proximal port distal to theproximal piston; and

first and second tubes, the first tube coupling one of the proximalports to one of the distal ports, and the second tube coupling the otherone of the proximal ports to the other one of the distal ports, suchthat:

(a) proximal motion of the proximal piston drives liquid through one ofthe tubes to apply a positive pressure to a first side of the distalpiston to displace the distal piston in a first direction and actuatethe tool to be in a first state, and

(b) distal motion of the proximal piston drives liquid through the otherone of the tubes to apply a positive pressure to a second side of thedistal piston to displace the distal piston in a second direction andactuate the tool to be in a second state.

In an embodiment, the tool, the distal cylinder, the distal piston andthe tube are adapted to be passed through a working channel of anendoscope so as to access a region within the body using the endoscope.

In an embodiment, the tool is adapted to access a portion of agastrointestinal tract of the patient

For some applications, the tool includes a biopsy tool and/or atherapeutic tool.

In an embodiment, the proximal piston is adapted to be hand operated.For example, the apparatus may include a linkage, coupled to theproximal piston, which is adapted to facilitate hand operation of theproximal piston.

There is still further provided, in accordance with an embodiment of thepresent invention, endoscopic apparatus having a distal end forinsertion into a body of a patient and a proximal end that is heldoutside the body of the patient, the apparatus including:

first and second proximal cylinders, disposed in a vicinity of theproximal end of the endoscopic apparatus;

first and second proximal pistons, slidably contained within therespective proximal cylinders;

at least one distal cylinder, disposed in a vicinity of the distal endof the endoscopic apparatus;

at least one distal piston, slidably contained within the at least onedistal cylinder;

a first tube for containing a liquid, coupled between the first proximalcylinder and the at least one distal cylinder;

a second tube for containing a liquid, coupled between the secondproximal cylinder and the at least one distal cylinder;

a mechanical linkage, coupled to the first and second proximal pistonsso as to:(a) move the first proximal piston and cause positive pressurein the first tube when the mechanical linkage is displaced in a firstdirection, and (b) move the second proximal piston and cause positivepressure in the second tube when the mechanical linkage is displaced ina second direction; and

a tool coupled to be actuated by displacement of the at least one distalpiston, so as to perform a mechanical action on tissue of the body orcontents of the body, responsive to displacement of the distal piston.

The present invention will be more fully understood from the followingdetailed description of the preferred embodiments thereof, takentogether with the drawings, in which:

BRIEF DESCRIPTION OF TIE DRAWINGS

FIG. 1 is a schematic, sectional drawing of an endoscopic toolcomprising a hydraulic actuation mechanism, according to a preferredembodiment of the present invention;

FIG. 2 is a schematic, sectional drawing of an endoscopic toolcomprising a hydraulic actuation mechanism, according to anotherpreferred embodiment of the present invention;

FIG. 3 is a schematic, sectional drawing of an endoscopic toolcomprising a hydraulic actuation mechanism, according to yet anotherpreferred embodiment of the present invention;

FIG. 4 is a schematic, sectional drawing of an endoscopic toolcomprising a hydraulic actuation mechanism, according to still anotherpreferred embodiment of the present invention;

FIG. 5 is a schematic, sectional drawing of an endoscopic toolcomprising a hydraulic actuation mechanism, according to a furtherpreferred embodiment of the present invention; and

FIG. 6 is a schematic, sectional drawing of an endoscopic toolcomprising a hydraulic actuation mechanism, according to yet a furtherpreferred embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference is now made to FIG. 1, which is a schematic sectional drawingof a flexible endoscopic device 100 comprising a hydraulically-actuatedtool, in accordance with a preferred embodiment of the presentinvention. Endoscopic device 100 comprises a distal portion 102, whichis advanced through a working channel 82 of an endoscope 80 placed inthe gastrointestinal tract of a patient. Device 100 additionallycomprises a proximal portion 104, part of which remains external to thepatient and is accessible to the operator of the tool. Typically, thetool comprises a biopsy tool 115, comprising two opposable biopsy jaws114. Tool 115 is disposed near the distal tip of device 100, forexcising or sampling tissue inside the gastrointestinal tract.

Means for actuating tool 1 15 are located near the distal tip of portion102. In a preferred embodiment, biopsy jaws 114 each comprise aspoon-shaped lever and rotate about a common pivot point 113, such thatthe spoon portion of each lever is able to grab and dissect tissue.Pivot point 113 is coupled to an end cap 112, which is coupled to thedistal tip of device 100. Movement of a wedge-shaped member 110 actuatesjaws 114, such that distal motion of member 110, i.e., motion in adistal direction (upward in the view shown in the figure), causesclosing of the biopsy jaws, while proximal motion of member 110, i.e.,motion in the proximal (downward) direction, allows the biopsy jaws toopen. In a preferred embodiment, tool 115 comprises a spring 130, whichacts to open biopsy jaws 114 when member 110 moves proximally.

Mechanical stops 118 are preferably coupled to the inside of portion102, distal to piston 108, to limit the motion of the piston whenpositive pressure is applied. Typically, when device 100 is advancedthrough working channel 82, pressure is applied to piston 108 so as topress piston 108 against stops 118 and maintain jaws 114 in the closedposition.

Member 110 is coupled to a distal piston 108 by a rod 120, such thatmovement of piston 108 causes an equal movement of member 110.Preferably, rod 120 has a length to diameter ratio that is relativelysmall (for example less that 10), such that rod 120 can transmitcompressive loads without buckling or appreciable bending.Alternatively, rod 120 may be absent, such that piston 108 is directlyfixed to member 110.

Actuation of tool 115 is achieved by movement of a proximal piston 106,which varies the pressure of a liquid-filled duct 116, intermediate topiston 106 and piston 108, so as to control the force acting on piston108. Preferably, duct 116 is filled with a substantially-incompressiblebiocompatible liquid (for example water or saline solution).Pressurizing duct 116 using piston 106 drives piston 108 in the distaldirection, thereby closing jaws 114. The operator initiates movement ofpiston 106 via a mechanical linkage 122, which is coupled to piston 106and accessible near the distal end of portion 104. In a preferredembodiment, linkage 122 is a simple rod, whose motion is directlyimparted to piston 106. Alternatively, linkage 122 comprises a joystick,wheel, or other mechanism to improve the ease of use of the tool, forexample by reducing the force required of the operator. It is noted thatuse of proximal piston 106 eliminates the more complex proximal pressureapparatus required by hydraulic endoscopic biopsy tools known in theart.

FIG. 2 is a schematic sectional drawing of a flexible endoscopic device200 comprising a hydraulically-actuated tool, in accordance with apreferred embodiment of the present invention. Device 200 generallyfunctions in a manner similar to that of device 100 describedhereinabove with reference to FIG. 1, but comprises different mechanismfor transferring motion of piston 108 into actuation of a biopsy tool117.

Movement of piston 108, due to pressure in duct 116, is transferred torod 120, to linkage members 124, and to the proximal end of biopsy jaws114. In this manner, distal motion of piston 108 tends to open jaws 114and to stretch spring 130, while proximal motion of piston 108 tends toclose jaws 114 with the assistance of spring 130. Closingjaws 114 ofbiopsy tool 117 thus induces tension in rod 120 and linkage members 124,minimizing the possibility of buckling of these parts. Additionally, bymodifying the size of the elements in the linkage of tool 117, the forceapplied by biopsy jaws 114 can be regulated to be a desL cd multiple ofthe force applied to piston 106.

It is noted that use of proximal piston 106 eliminates the more complexproximal pressure apparatus required by hydraulic endoscopic biopsytools known in the art.

FIG. 3 is a schematic sectional drawing of a flexible endoscopic device400 comprising a hydraulically-actuated tool 412, in accordance with apreferred embodiment of the present invention. Means for facilitatingoperation of the tool are located in portion 102, and preferablycomprise a plurality of cylinders 328, each of which having disposedtherein a piston 310. Advantageously, a plurality of cylinders 328provides the physician with the ability to independently control eitherone of jaws 114, e.g., so as to be able to operate tool 412 off of thecenter line of endoscopic device 400. It will be appreciated that otherendoscopic tools or sets of tools (not shown) used in other applicationsalso benefit from the increased degrees of freedom provided by aplurality of cylinders 328.

Each piston 310 is preferably coupled to one end of respective wires302. The opposite ends of wires 302 are coupled to respective portionsof biopsy jaws 114. In a preferred embodiment, a crosspiece 304, whichis coupled to portion 102, comprises a plurality of pulleys 306, so asto route wires 302 between pistons 310 and jaws 114.

Movement of pistons 310 is driven by liquid delivered to or withdrawnfrom cylinders 328 via flexible tubes 402. Preferably, each cylinder 328is aligned parallel to the longitudinal axis of the endoscope, andliquid is delivered to or withdrawn from a port 414 near the distal endof the cylinder. Each cylinder is thus divided into two sections bypiston 310: (a) a liquid transfer section 308, closer to the distal endof portion 102, where liquid is delivered or withdrawn, and (b) apassive section 312, closer to the proximal end of portion 102.

A spring 326 is preferably coupled to biopsy jaws 114, so as to tend toopen the jaws. There is thus minimal or no use of suction applied tocylinders 328 to move pistons 310 distally and open jaws 114. Thisreduced use of suction decreases potential problems associated withcollapse of flexible tubes 402. Also, suction as a means for generatinguseful motion of the endoscope is generally limited to one atmosphere,while positive pressure can exceed one atmosphere. Experiments performedusing th prciples of he present nr h av enerated pressures of 50atmospheres at the distal end, using only the force easily generated byhand, applied to the simple and inexpensive apparatus preferred inaccordance with these embodiments of the present invention. It isemphasized that prior art systems for hydraulic endoscopic biopsy toolsgenerally require complicated and expensive apparatus, which utilizepumps and pressure-regulation apparatus or other powered equipment tooperate.

For some applications, passive section 312 of each cylinder 328comprises an orifice 408, allowing a fluid (typically air) to enter orleave as piston 310 is displaced. In a preferred embodiment of thepresent invention, the passive section of cylinder 328 comprises anelastic element such as a spring, optionally replacing spring 326, whichacts to maintain piston 310 in its equilibrium position. Alternatively,the passive section of cylinder 328 is sealed and encloses acompressible fluid such as air, which acts like a spring when piston 310is displaced, returning the piston to its equilibrium position.

Liquid is delivered to or withdrawn from each cylinder 328 responsive tothe operation of a corresponding drive-piston 406 in a drive-cylinder404. Each drive-piston 406 is preferably coupled to the respectivecylinder 328 by one of flexible tubes 402. Applying a distally-directedforce to drive-piston 406 pressurizes the liquid in drive-cylinder 404.This pressure is transmitted through the liquid in tube 402 and incylinder 328, and comes to act on piston 310, to cause actuation of tool412 as described hereinabove. In particular, distal motion of pistons406 causes closing of jaws 114, while expansion of spring 326 causesopening of jaws 114. The ratio of the driving force applied todrive-piston 406 to the pressure force received by piston 310 isgenerally proportional to the area ratio of the two piston faces. Thus,fine control of tool 412 can be achieved by decreasing the area ofpiston 406 relative to the area of piston 310. In this manner,operator-induced motions of piston 406 can be leveraged to yield finemotions of piston 310. The force required to actuate the tool can beselected by sizing drive-piston 406 and piston 310 appropriately.

In some preferred embodiments of the present invention, a mechanicallinkage 410 such as a joystick mechanically coupled to pistons 406, isused to actuate drive-pistons 406 to make actuating the tool moreergonomic. For applications in which more cylinders are used at thedistal and/or proximal ends of the en-udosc-ope, appropriate changes inthe linkage are provided, so as to facilitate greater ease of use forthe operator.

FIG. 4 is a schematic sectional drawing of a flexible endoscopic device460 comprising a hydraulically-actuated tool 450, in accordance with apreferred embodiment of the present invention. As described hereinabovewith reference to FIG. 1, movement of wedge-shaped member 110 actuatesbiopsy jaws 114, such that distal motion of member 110 causes closing ofthe biopsy jaws, while proximal motion allows the biopsy jaws to open.In contrast to some known hydraulic biopsy tool control apparatus, tool450 preferably does not include a spring to open or close biopsyjaws114.

Actuation of tool 450 is initiated by movement of drive-piston 406controlled by the operator. Motion of drive-piston 406 varies thepressure in a distal flexible tube 316 and a proximal flexible tube 314;which, respectively, couple: (a) a distal drive-portion 322 ofdrive-cylinder 404 to a distal portion 309 of cylinder 328, and (b) aproximal drive-portion 324 of drive-cylinder 404 to a proximal portion313 of cylinder 328. In this manner, fine control of the force acting onpiston 310 is typically achieved. Preferably, tubes 314 and 316 arefilled with a substantially-incompressible biocompatible liquid (forexample water or saline solution).

The operator initiates movement of piston 406 via mechanical linkage122, which is coupled to piston 406 and is accessible near the proximalend of portion 104. Advantageously, movement of piston 310 in both theproximal and the distal direction is achieved by application of positivepressure into tubes 316 and 314, respectively. In particular, proximalmotion of drive-piston 406 closes jaws 114, and distal motion ofdrive-piston 406 opens jaws 114. Thus, the embodiment of the presentinvention shown in FIG. 4 performs active work in both directions inresponse to the application of positive pressure, typically without theuse of a spring. Advantageously, high levels of positive hydraulicpressure are easily generated to both open and close biopsy jaws or toappropriately actuate other endoscopic tools.

FIG. 5 is a schematic sectional drawing of flexible endoscopic device400, comprising hydraulically-actuated tool 412, in accordance with apreferred embodiment of the present invention. The embodiment shown inFIG. 5 is generally similar to that shown in FIG. 3, except in thatmechanical linkage 410 (which is shown in FIG. 3 as having twojoysticks), is replaced in FIG. 5 by a single joystick 500. Whenjoystick 500 is moved in one direction by a user, pressure in one ofdrive-cylinders 404 is increased, producing a corresponding increase inthe pressure in the flexible tube 402 coupled thereto. When joystick 500is moved in the other direction, pressure in the other one ofdrive-cylinders 404 is increased, producing a corresponding increase inthe pressure in the flexible tube 402 coupled to that drive-cylinder.

FIG. 6 is a schematic sectional drawing of a flexible endoscopic device600 comprising a hydraulically-actuated snare 602, in accordance with apreferred embodiment of the present invention. Endoscopic device 600 isgenerally similar to endoscopic device 460, described hereinabove withreference to FIG. 4, except in that biopsy jaws 114 and relatedapparatus shown in FIG. 4 are replaced in the embodiment shown in FIG. 6by snare 602. Snare 602 is typically used to surround a polyp or otherportion of tissue of a patient. When the snare is gradually withdrawninto a casing 604 thereof, which is mounted to a distal end-piece 612 ofendoscopic device 600, the tissue is thereby removed

Actuation of snare 602 is initiated by movement of drive-piston 406.Motion of drive-piston 406 varies the pressure in distal flexible tube316 and proximal flexible tube 314, as described hereinabove. In thismanner, fine control of the force acting on piston 310 is typicallyachieved. Motion of piston 310, in turn, is preferably directlyconverted to actuation (i.e., opening or closing) of snare 602. Openingand closing of snare 602 is thus typically achieved by application ofpositive pressure into tubes 314 and 316, respectively.

It will be appreciated that snare 602 could be replaced by a retractableforceps or other medical tools kmown in the art.

In a preferred embodiment of the present invention, techniques describedherein are applied in conjunction with methods and apparatus describedin a co-pending U.S. provisional patent application, tentative serialNo. 60/395,694, entitled, “Piston-actuated endoscopic steering system,”filed Jul. 11, 2002, which is assigned to the assignee of the presentpatent application and is incorporated herein by reference. That patentapplication states:

-   -   “In preferred e-rbodiment of the present invention, a distal        section of a flexible endoscope is advanced through the        gastrointestinal tract with the aid of a steering mechanism near        the distal end of the endoscope. The steering mechanism        comprises one or more cylinders, each containing a piston,        wherein movement of one or more of the pistons actuates rods,        wires and/or cables in the steering mechanism to cause turning        of the distal end of the endoscope. Movement of the one or more        pistons is achieved by introducing or removing fluid into/from        the corresponding cylinders, so as to cause a motion of the        piston. The fluid is delivered from the proximal end of the        endoscope to the cylinders of the steering mechanism near the        distal end of the endoscope via a closed system of flexible        tubes.”

Alternatively or additionally, techniques described herein are appliedin conjunction with methods and apparatus described in PCT PatentPublication WO 00/44275, entitled, “Propulsion of a probe in the colonusing a flexible sleeve,” and U.S. Pat. application Ser. No. 09/646,941in the national phase thereof, which are assigned to the assignee of thepresent patent application and are incorporated herein by reference. The'275 publication states:

-   -   “In preferred embodiments of the present invention, a probe        containing an endoscopic instrument is advanced through the        lower gastrointestinal tract of a patient by inflation of a        flexible sleeve coupled to the probe. One end of the sleeve is        anchored, typically at or adjacent to the patient's anus. As the        sleeve is inflated, preferably using a pressurized gas, the        probe is propelled forward, and the sleeve is fed out gradually        between the probe and the anus.

The portion of the sleeve that is inflated expands radially outward andremains substantially stationary relative to the intestinal wall as longas it is inflated.

Longitudinal motion of the sleeve relative to the wall generally occursonly at and adjacent to the probe itself. The probe is thus advancedeasily, and trauma to the gastrointestinal tract is minirnized. Toremove the probe, the sleeve is deflated and is used to pull the probeback out through the anus. . . “In other preferred embodiments of thepresent invention, the sleeve is stored in a compact state, typicallyfolded or rolled up, inside or immediately adjacent to the probe. Mostpreferably, the folded or rolled-up probe is stored in a recess in aproximal portion of the probe. As tie probe advances, the sleeve feedsgradually out of its stored state and expands against the intestinalwall. . . “In preferred embodiments of the present invention, advancingthe probe through the gastrointestinal tract by way of inflating thesleeve reduces or eliminates the necessity of applying mechanical forceat a proximal end of the probe (outside the patient's body) to insertthe probe, as is required using conventional endoscopes. The presentinvention thus reduces or eliminates the necessity of applyingconcentrated, local pressure to any part the patient's body, reduces oreliminates rubbing and friction between the unit or parts of it and thepatient's body, and avoids ejecting fluids or other materials into thebody's passageway.”

-   -   In accordance with a preferred embodiment of the present        invention, by combining the techniques of the present patent        application with the techniques described in the        “Piston-actuated endoscopic steering system” application and the        “Propulsion of a probe in the colon using a flexible sleeve”        application, an endoscope is provided which performs        substantially all motions (i.e., tool-operation, steering and        propulsion) without the need for wires or other elements which        are known to sometimes apply undesired forces to the        gastrointestinal tract and/or to generate excess friction forces        during operation.

It will be appreciated that the preferred embodiments described aboveare cited by way of example, and that the present invention is notlimited to what has been particularly shown and described hereinabove.Rather, the scope of the present invention includes both combinationsand subcombinations of the various features described hereinabove, aswell as variations and modifications thereof which would occur topersons skilled in the art upon reading the foregoing description andwhich are not disclosed in the prior art. For example, althoughpreferred embodiments of the present invention have been describedherein with respect to a hydraulic tool for operation in thegastrointestinal tract, it will be appreciated that these techniques maybe adapted for use in other body cavities as well.

1. Endoscopic apparatus having a distal end for insertion into a body ofa patient and a proximal end that is held outside the body of thepatient, the apparatus comprising: a proximal cylinder, disposed in avicinity of the proximal end of the endoscopic apparatus; a proximalpiston, slidably contained within the proximal cylinder;a distalcylinder, disposed in a vicinity of the distal end of the endoscopicapparatus; a distal piston, slidably contained within the distalcylinder; a tube for containing a liquid, coupled between the proximaland distal cylinders; and a tool coupled to be actuated by displacementof the distal piston, so as to perform a mechanical action on tissue ofthe body or contents of the body, responsive to displacement of thedistal piston.
 2. Apparatus according to claim 1, wherein the tool, thedistal cylinder, the distal piston and the tube are adapted to be passedthrough a working channel of an endoscope so as to access a regionwithin the body using the endoscope.
 3. Apparatus according to claim 1,wherein the tool is adapted to access a portion of a gastrointestinaltract of the patient.
 4. Apparatus according to claim 1, wherein thetool comprises a biopsy tool.
 5. Apparatus according to claim 1, whereinthe tool comprises a therapeutic tool.
 6. Apparatus according to claiml,wherein the distal cylinder has two regions, on respective sides of thedistal cylinder, wherein the tube is adapted to be in communication witha first one of the regions, wherein a second one of the regions isconfigured such that motion of the distal piston in a first directionchanges a fluid pressure in the second region, and wherein the distalpiston is coupled to the distal cylinder so as to experience a force ina second direction, opposite to the first direction, responsive to thechange in fluid pressure.
 7. Apparatus according to claim 1, wherein theproximal piston is adapted to be hand operated.
 8. Apparatus accordingto claim 7, wherein the apparatus comprises a linkage, coupled to theproximal piston, which is adapted to facilitate hand operation of theproximal piston.
 9. Apparatus according to claim 1, wherein the tool iscoupled to the distal piston so as to be actuated by pressurization ofthe tube by the liquid due to operation of the proximal piston. 10.Apparatus according to claim 9, wherein the tool comprises a forceps,and wherein actuating the tool by pressurization of the tube causes theforceps to close.
 11. Apparatus according to claim 9, wherein the toolcomprises a snare, and wherein actuating the tool by pressurization ofthe tube causes the snare to close.
 12. Endoscopic apparatus having adistal end for insertion into a body of a patient and a proximal endthat is held outside the body of the patient, the apparatus comprising:a distal piston; a distal cylinder within which the distal piston isslidably contained, and which is in a vicinity of the distal end of theendoscopic apparatus, the distal cyiinder having a first distaI portproximal to the distal piston and a second distal port distal to thedistal piston; a tool coupled to be actuated by displacement of thedistal piston;a proximal piston ; a proximal cylinder within which theproximal piston is slidably contained, and which is in a vicinity of theproximal end of the endoscopic apparatus, the proximal cylinder having afirst proximal port proximal to the proximal piston and a secondproximal port distal to the proximal piston; and first and second tubes,the first tube coupling one of the proximal ports to one of the distalports, and the second tube coupling the other one of the proximal portsto the other one of the distal ports, such that: (a) proximal motion ofthe proximal piston drives liquid through one of the tubes to apply apositive pressure to a first side of the distal piston to displace thedistal piston in a first direction and actuate the tool to be in a firststate, and (b) distal motion of the proximal piston drives liquidthrough the other one of the tubes to apply a positive pressure to asecond side of the distal piston to displace the distal piston in asecond direction and actuate the tool to be in a second state. 13.Apparatus according to claim 12, wherein the tool, the distal cylinder,the distal piston and the tube are adapted to be passed through aworking channel of an endoscope so as to access a region within the bodyusing the endoscope.
 14. Apparatus according to claim 12, wherein thetool is adapted to access a portion of a gastrointestinal tract of thepatient.
 15. Apparatus according to claim 12, wherein the tool comprisesa biopsy tool.
 16. Apparatus according to claim 12, wherein the toolcomprises a therapeutic tool.
 17. Apparatus according to claim 12,wherein the proximal piston is adapted to be hand operated. 18.Apparatus according to claim 17, wherein the apparatus comprises alinkage, coupled to the proximal piston, which is adapted to facilitatehand operation of the proximal piston.
 19. Endoscopic apparatus having adistal end for insertion into a body of a patient and a proximal endthat is held outside the body of the patient, the apparatus comprising:first and second proximal cylinders, disposed in a vicinity of theproximal end of the endoscopic apparatus; first and second proximalpistons, slidably contained within the respective proximal cylinders; atleast one distal cylinder, disposed in a vicinity of the distal end ofthe endoscopic apparatus; at least one distal piston, slidably containedwithin the at least one distal cylinder; a first tube for containing aliquid, coupled between the first proximal cylinder and the at least onedistal cylinder; a second tube for containing a liquid, coupled betweenthe second proximal cylinder and the at least one distal cylinder; amechanical linkage, coupled to the first and second proximal pistons soas to: (a) move the first proximal piston and cause positive pressure inthe first tube when the mechanical linkage is displaced in a firstdirection, and (b) move the second proximal piston and cause positivepressure in the second tube when the mechanical linkage is displaced ina second direction; and a tool coupled to be actuated by displacement ofthe at least one distal piston, so as to perform a mechanical action ontissue of the body or contents of the body, responsive to displacementof the distal piston.